How can I get the number of CPU cores in Powershell?

Suppose I'm running a PowerShell session on a Windows machine.

Is there a one-liner I could use to get:

The number of physical processor cores and/or
The max number of in-flight threads, i.e. cores * hyper-threading factor?

Note: I want just a single number as the command output, not any headers or text.

Solution

Note:

The answer in the next section assumes a single processor (socket) with multiple cores.
According to documentation of the Win32_Processor CIM/WMI class, an instance of that class exists for each processor (socket), so if your system has multiple processors (each with multiple cores) installed, use something like the following to get the total count of logical cores (.NumberOfLogicalProcessors); use .NumberOfCores for the physical cores:
```
$totalLogicalCores = (
 (Get-CimInstance –ClassName Win32_Processor).NumberOfLogicalProcessors |
   Measure-Object -Sum
).Sum
```
- Note that there's also a .NumberOfEnabledCore [sic] property (Windows 10+, Windows Server 2016+), which refers to enabled physical cores, according to the docs. There's seemingly no distinct property for the hyperthreading multiplication factor, so in order to determine the enabled logical core count, you may have to to use .NumberOfEnabledCore * (.ThreadCount / .NumberOfCores)

Ran Turner's answer provides the crucial pointer, but can be improved in two ways:

The CIM cmdlets (e.g., Get-CimInstance) superseded the WMI cmdlets (e.g., Get-WmiObject) in PowerShell v3 (released in September 2012). Therefore, the WMI cmdlets should be avoided, not least because PowerShell (Core) (v6+), where all future effort will go, doesn't even have them anymore. Note that WMI still underlies the CIM cmdlets, however. For more information, see this answer.
Format-Table, as all Format-* cmdlets, is designed to produce for-display formatting, for the human observer, and not to output data suitable for later programmatic processing (see this answer for more information).
- To instead create objects with a subset of the input objects' properties, use the Select-Object cmdlet. (If the output object(s) have 4 or fewer properties and aren't captured, they implicitly format as if Format-Table had been called; with 5 or more properties, it is implicitly Format-List).

Therefore:

# Creates a [pscustomobject] instance with 
# .NumberOfCores and .NumberOfLogicalProcessors properties.
$cpuInfo =
  Get-CimInstance –ClassName Win32_Processor | 
     Select-Object -Property NumberOfCores, NumberOfLogicalProcessors

# Save the values of interest in distinct variables, using a multi-assignment.
# Of course, you can also use the property values directly.
$coreCountPhysical, $coreCountLogical = $cpuInfo.NumberOfCores, $cpuInfo.NumberOfLogicalProcessors

Of course, if you're only interested in the values (CPU counts as mere numbers), you don't need the intermediate object and can omit the Select-Object call above.

As for a one-liner:

If you want a one-liner that creates distinct variables, without repeating the - costly - Get-CimInstance call, you can use an aux. variable that takes advantage of PowerShell's ability to use assignments as expressions:

$coreCountPhysical, $coreCountLogical = 
  ($cpuInfo = Get-CimInstance -ClassName Win32_Processor).NumberOfCores, 
  $cpuInfo.NumberOfLogicalProcessors

To save the numbers in distinct variables and output them (return them as a 2-element array), enclose the entire statement in (...).
To only output the numbers, simply omit the $coreCountPhysical, $coreCountLogical = part.